The present invention relates to a handlebar stem structure that includes two extensions threadedly connected to a tube and a resin layer and a fiber layer are coated to the extensions and the tube.
A conventional bicycle handlebar stem is a one-piece member which is made by metal. One end of the handlebar stem is connected to the steerer tube extending from the head tube, the other end of the handlebar is connected to the handlebar. The metal handlebar stem is too heavy and does not meet the requirement of the modern design of bicycles. Manufacturers develop a handlebar stem that is made by composite material. This type of handlebar stem is composed of two parts which connected by bolts. Each part requires a set of mold and the length of the handlebar stem is fixed so that the manufacturers need many sets of molds for manufacturing the handlebars having different length.
In accordance with one aspect of the present invention, there is provided a handlebar stem structure which comprises a tube for receiving a steerer tube and the tube has two connection members extending radially outward from an outer periphery of the tube. Two extensions are movably connected to the two connection members. Each of the two extensions has two connection ports. An outer layer is coated to the tube and the connection members. The connection ports extend from the outer layer and a first recess is defined in the outer layer. A retaining member is connected to the two connection ports and a second recess is defined in an inside of the retaining member. The first recess and the second recess are matched to form a passage for receiving a handlebar.
The primary object of the present invention is to provide a handlebar stem whose length can be adjustable before being coated with the outer layer.
The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.